Conventionally, a cutting apparatus and a cutting method for coated optical fibers, as shown in FIGS. 14A and 14B, are known (see, e.g., Patent Document 1). The optical fiber cutting apparatus 100 includes a blade 101, and pairs of upper and lower clamps 104a, 104b disposed on respective sides of the blade 101 to hold bare fibers 103 of a ribbon 102. Further, on an opposite side of the blade 101 with respect to the bare fibers 103, a support portion 105 is disposed so as to be movable in up-and-down directions.
As shown in FIG. 14A, when cutting the coated optical fibers with this optical fiber cutting apparatus, the bare fibers 103 are held by the respective clamps 104a, 104b, 104a, 104b, and then, a slit is formed on a surface of each of the bare fibers 103 by moving the blade 101 in a direction orthogonal to a longitudinal direction of the bare fibers 103 (i.e., a direction from a front side to a rear side of the drawing sheet). Further, as shown in FIG. 14B, the support portion 105 is moved in a downward direction in the drawing to apply an external force on the bare fibers 103 with the slits being on the outer side, whereby the bare fibers 103 are cleaved.
Patent Document 1: Japanese Unexamined Patent Publication: JP 11-264909 A (FIG. 4, FIG. 6)
According to the optical fiber cutting apparatus and the cutting method as described in Patent Document 1, when cutting the coated optical fibers, generally, glass fibers are cut by a special cutter after removing the coatings with a coating remover. Core diameters of the optical fibers are small, which is φ10 μm in a single mode and φ50-62.5 μm in a multi mode. Therefore, in order to reduce connection loss, positioning accuracy of micrometer order is required. However, with the coatings, it is difficult to ensure positioning accuracy due to deformation and thickness deviation of the coatings. Further, since a condition of a cut end face affects the connection loss, it is required to perform mirror finishing with a special tool, which is an onerous work.
In recent years, coated optical fibers are sometimes being cut without removing the coatings, complying with a demand to simplify optical connections. When cutting the coated optical fibers with the existing cutter, firstly, it is necessary to form a cut into each of the coatings before forming a slit on the surface of each of the glass fibers. However, when trying to cut the coatings in a state shown in FIG. 14A, clamping the respective sides of the coated optical fibers with the two pairs of clamps 104a, 104b, 104a, 104b does not provide enough resisting force so that the coated optical fibers move away from the blade 101. Therefore, the slits cannot be formed on the surfaces of the glass fibers. Further, in order to have the cleaved faces of the glass fibers to be mirrored faces, it is necessary to apply an appropriate tension to the optical fibers. Thus, a clamping force cannot be increased indiscreetly to gain the resisting force.